The invention generally relates to replaceable air filters, and, more particularly to a re-usable frame support rack for supporting and retaining an outstretched, replaceable pleated-media filter core. The frame support rack in accordance with the invention is available in various standard as well as custom sizes, but generally speaking, it is more advantageous in relatively large sizes as commonly used by commercial, industrial, and municipal users, and not so much by residential users.
Conventional air filters typically comprise a complete package of a filter core and a rigid frame surrounding and permanently attached to the filter core. The filter core is typically formed from conventional filter media. The rigid frame is typically formed from paperboard or the like. Commercial, industrial, and municipal users typically have defined service policies for the replacement of spent air filters after the filters have outlasted their usefulness. These kinds of users typically will keep a stock of fresh conventional filters on supply in a stock room for replacement purposes. Service personnel are responsible for replacing spent filters with fresh filters and then disposing of the spent filters. With conventional filters, each time a filter is replaced a complete package is discarded as refuse, comprising the rigid frame and its attached filter core.
It is an object of the invention to provide a re-usable frame support rack to combine with a replaceable filter core, such as for example a core comprising pleated filter media, in order to provide economy in filter replacement costs, service personnel labor costs, stock room storage space requirements, refuse volume, and so on.
It is known in the art, however, to provide a fixed frame for supporting a pleated-media filter core. To assign reference directions to the pleated-media core, it stretches out in a longitudinal direction, and its pleats or fold-lines extend in a transverse direction. A prior art fixed frame is constructed from a single straight channel piece. In fabrication, the straight channel will be notched at the location of the four corners of the frame. Then the notched straight-channel piece will be bent into the rectangle shape of the frame, and welded or brazed tight. The final frame thus will have opposite longitudinal channel sections facing each other (as well as opposite transverse channel sections too). The spaced, facing channel sections act to cup the spaced longitudinal margins of the outstretched pleated-media filter core.
Given a typical orientation, the opposite longitudinal channel sections usually define the top and bottom borders of the prior art fixed frame. The top and bottom channels protect the pleated media of the filter core from damage during installation of the frame in any given on-site air-handling system. That is, the fixed frame usually installs in the on-site air-handling equipment by sliding into opposed tracks or slideways for it in a filter-station of the on-site air-handling equipment. Therefore, the top and bottom channels of the frame consequently provide the following features:--(i) the top and bottom channels act as bearing surfaces to facilitate sliding in the slideways, and (ii) the top and bottom channels protect the pleated media of the filter core from damage such as being grabbed, torn or otherwise pulled at by the slideways of the on-site air-handling equipment.
There are shortcomings with the prior art fixed frame for pleated-media filter core. The pleated-media filter core can only be loaded and unloaded into the rigidly spaced top and bottom channel sections, and then stretched out between the left and right channels sections, in an awkward way. To load the filter core, the pleated-media must start out substantially collapsed, and then it is placed in the interspace between the top and bottom channels twisted slightly off-angle. The collapsed media is next twisted perpendicular to the opposed top and bottom channels such that its opposite edges insert between and are hence cupped by the opposed top and bottom channels. After that, the pleated-media is stretched out to the left and right extremes, all while its opposite longitudinal edges are sliding in the top and bottom channels to unfold to its fully outstretched use position.
The filter core is unloaded from the prior art frame by the reverse steps. More particularly, the filter core is collapsed by sliding its longitudinal edges in the opposed top and bottom channels until substantially collapsed. The collapsed filter core is then twisted such that its longitudinal edges twist out of the top and bottom channels. Once that has been accomplished, the filter core can be lifted out away from the fixed frame.
In view of the foregoing shortcomings of the prior art, it is an object of the invention to provide a re-usable frame support rack for replaceable pleated-media filter core which allows loading and unloading by means of much less fuss.
A number of additional features and objects will be apparent in connection with the following discussion of preferred embodiments and examples.